As a countermeasure to the serious environmental problem of global warming, it is required in recent years to substantially decreasing the greenhouse effect by various so-called greenhouse gases of which carbon dioxide is one of the most notorious pollutant gases. Reducing of carbon dioxide in the aerospace can be accomplished by decreasing emission of the gas but can also be accomplished by increasing fixation or immobilization of the carbon dioxide gas from emission sources.
A great variety of proposals are made heretofore for the ways of fixation of carbon dioxide in an emission source including absorption in the oceanic water, electrochemical reactions for the synthesis of hydrocarbon compounds such as methane or alcoholic compounds such as methanol from carbon dioxide, quasi-photosynthesis reaction for the synthesis of methanol and so on. Though limited to a laboratory scale experimentation, a method has been developed for the fixation of carbon dioxide gas to produce a carboxylic acid by a quasi-enzymatic reaction in the presence of a metal complex catalyst or in an organic synth sis reaction.
It is a general tr nd in recent years in this regard that certain enzymatic reactions have made their second debut by virtue of their advantages of the relatively small load imposed on the environment. This advantage of low load on the environment, however, can hardly be obtained in the fixation of carbon dioxide according to the above mentioned various methods because of the considerably large energy consumption in the methods and indispensability of using an organic solvent in the reactions.
A report is also available of utilization of an enzymatic reaction for fixation of carbon dioxide. The enzymatic reaction so far developed, however, is limited to the enhancement of water-solubility of carbon dioxide by means of a carbonate dehydratase.